Create email alias for user/subscriber

I would like to programmatically or automatically create an email alias for a new user and display it in that user’s account somewhere so he/she can use it. It could be based on username or preferably user ID, for example: [email protected], as an alias or relay email (not two way, just for the initial contact). This would be used for a networking site. So, not only could users be contacted via the contact form on their specifically assigned profile page or post, but could also be reached via email relay without revealing own email address. Any idea how this can be accomplished? Creating the email address via the host would be manual and not feasible in high volume. Can’t find a plugin that addresses anything similar. I know some have tried to address it in creating a type of Craigslist clone but it does seem to be a tough one. Again, I don’t need it to be a back and forth. The user can decide whether or not to respond to the sender, thereby revealing the personal email address. I only need it to be a relay or alias. Bonus if it can do the back and forth, like Craigslist, but not essential. Any idea how I can make this happen or someone that could build it?